I suppose I should make it clear at the outset that I refer to a practical ethics. "Practical" of course implies an ethics which is intended to apply to the way we live. Ethics in philosophy, unfortunately, seems to have little to do with our lives and how we should live them (though there seems to be a resurgence of virtue ethics and, most fortunately, stoicism even among professional philosophers). But those who are still debating whether there is an independently existing world can't be expected to concern themselves seriously with what we should do in such a world, if indeed it exists.
They nonetheless do so concern themselves, of course; perhaps in what they would consider their free time. Even so, making the focus of one's intellect the raising and debating of questions which either have no answer at all or have no answer which makes any difference in life is indicative of a character which thrives on the abstract and academic rather than the resolution of real-life problems. There's nothing necessarily wrong with that, of course, but such a character is not helpful in resolving real life problems.
For some time, I've thought the suggestion, or command, that we love one another an impractical one, and so no basis on which life can be lived well and morally. I think it indisputable that we love, truly, only very few people, and that the prerequisites for love simply do not obtain in most cases. A certain intimacy with and knowledge of the loved one is required, and we don't have that with most people. The injunction that we love one another, therefore, is foolish. It will not happen; it clearly hasn't happened. As a result, it doesn't serve as a foundation for a practical ethics.
I think we can, though, respect one another without great effort, ceteris paribus. Respect may be a basis on which a "living" ethics may be based. Such respect has a prerequisite as well, however, but that prerequisite is knowledge of others but especially of ourselves.
Self-knowledge doesn't require self-love. In fact, it's inconsistent with excessive self-regard and egoism. Respect is an informed attitude; it's based on reasonable assessment. It's clearly unreasonable to regard oneself as especially and inherently favored, remarkable, significant, unique, when one inhabits a tiny world in an unremarkable galaxy in a vast universe. It's arguably delusional.
Even on a much smaller scale--focusing on our planet alone--it's unreasonable to think of oneself as remarkable merely because one exists. Billions of others of the same kind exist as well. If I am remarkable and significant simply by virtue of being, those like me are equally remarkable. There is no reason to think of oneself as more worthy than any other person, ceteris paribus, as a consequence. Or, for that matter, less worthy than any other person. We begin from a position of equality when it comes to worth. Respect involves the consideration of worth, it's based on the worth we accord someone or something. If we are entitled to respect, others are entitled to it as well (again, ceteris paribus).
We are beings having very similar basic characteristics and needs, even desires. We have the ability to think, and to act in certain ways. "Know thyself" said the Delphic Oracle. The more we know ourselves, the better we are able to determine what we are and are not capable of, what harms us and what benefits us. By knowing ourselves we know the same as to others, again in a basic but very fundamental sense.
There are basic needs, desires, abilities, emotions, characteristics we all share, and we can and should respect them in others just as we respect them in ourselves, and prefer others to respect them in us. This is something which is to be acknowledged, and once acknowledged this is something with which we may address questions relating to whether our needs and desires are to be given preference over those of others, which require the consideration of circumstances on a case by case basis. The questions become complex, of course, but this simple position may be used as a guideline. All to be worked out over time, of course, and subject to revision.
Why respect others if we respect ourselves? Stoicism offers reasons to do so which I personally accept, e.g. the fact that we all partake in and are part of a universe worthy of reverence, for example. From that premise, I think the ethics of respect follows with some celerity. But there obviously are those who don't accept such a premise, so I will try to take an approach which doesn't depend on such a belief.
Respect being the result of reasonable assessment, it must be reasonable not merely in self-assessment but in the assessment of others. We should have a reason for not respecting others. If we cannot reasonably maintain that we are entitled to respect more than others, then there is no reason not to accord them respect. A reason is required in order to withhold respect. We may irrationally claim that we're worthy of respect and others are not, due to a mental condition or because our assessment of our own value and those of others is uninformed, or because we are born in more favored circumstances than others, but these aren't reasonable bases on which to withhold respect, as they are not reasons for others to be respectful of us, nor are they reasons supporting self-respect.
Why be reasonable; why not do things without any reason, without thinking? Having reasons to act serves us well generally, much more than having no reasons. If such considerations don't suffice, ask me as well whether there is an independently existing world, while you're at it. This is, as I indicated, practical ethics.
While we start at a position of equal worth, and equal entitlement to respect, that of course may change. Some may through their conduct become the subject of greater or less respect, though basic respect must still be accorded to all.
What does this entail? Well, these are preliminary thoughts, after all.